Solutions for the distribution of traffic information in a public transport system are available on the market. One example of such a system is the AB Thoreb KomFram system which is successfully used in Europe, the USA and Asia. One problem with such systems is to establish databases having information about the routes along which the vehicles in the system are running; information which is subsequently used, for example, to procure information about between which stops a vehicle is positioned. The information consists of, among other things, tables of distances, i.e. lists with stops along different routes and the distances between the stops.
Nowadays, the most common method for establishing these tables of distances is simply to drive a measuring vehicle along the route and manually note the distances. These notes are then transferred to the database of the system in a suitable way. Although such recording of distances in a transport network can be provided relatively easily, it is not satisfactory for very long since the routes usually change. In a public transport network in a city, it is a matter of several changes every year, on the one hand, due to permanent re-routings and, on the other, due to temporary interference, such as road work. It is comprehensive work to keep the lists of distances continuously updated and, especially in the case of minor changes, there is a great risk that it is not done. The information in the system is thus degraded, which results in a risk of erroneous traffic information.
In addition, the above-described method of providing the system with information is impaired by several sources of errors. Reading from a vehicle, which typically takes place manually by looking at the trip meter of the vehicle, is difficult to make exact. When these notes are later transferred to the database, there is a risk of misreading and mistyping.
An alternative to providing the system with information about the distance between stops is to use GPS equipment in order to know continuously approximately where a vehicle is positioned. However, the disadvantage of GPS is that information about the position of the vehicle is sent only at predetermined intervals, and between these points the vehicle advances relatively far (up to about 30 m) and also the accuracy of the GPS system of +/−15 m has to be taken into consideration. Another disadvantage of GPS is that in cities with high buildings, for example in New York and Singapore, great problems may arise. Since the radio signal from a GPS satellite in such cities with high buildings sometimes does not reach the GPS receiver directly but indirectly via reflection into the front of a building or the like, the GPS receiver may exhibit considerable errors. A system is thus desirable which is more closely connected to information available in the vehicle's own information system.
A new driver needs to learn the different routes which he or she is to use and memorise them. To this end, a driving instructor, who knows the routes well, usually accompanies the new driver a number of trips until the new driver has been trained. This is very expensive for a transport company. The method has to be repeated for every new driver who is employed with the purpose of driving a bus in a predetermined area or traffic section.